I don't think I would use these stats to support the need for more immigration. They point directly to the fact that (mostly)illegals are taking jobs from our citizens.
That is exactly what is happening. Between the first quarter of 2000 and the first quarter of 2013, the native-born population accounted for two-thirds of overall growth in the working-age population (16 to 65), but none of the net growth in employment among the working-age has gone to natives.
The overall size of the working-age native-born population increased by 16.4 million from 2000 to 2013, yet the number of natives actually holding a job was 1.3 million lower in 2013 than 2000.
The total number of working-age immigrants (legal and illegal) increased 8.8 million and the number working rose 5.3 million between 2000 and 2013.